Badboy's E-M Diagrams

[PJ_Godzilla]

Gents, Does anyone know if Badboy maintains a repository (or perhaps suppository) of E-M comparisons? I've seen a link recently to his E-M page but saw no link to the oft-reffed "calculator" or any such repository. Badboy knows his stuff and I'm looking for a couple of specific E-Ms.   

[FLS]

Badboy has not published all his data but this should be a good link for his calculator if you want to do your own flight testing.

http://www.leonbadboysmith.com/Files/AH_BootStrap.zip

[Badboy]

I'm looking for a couple of specific E-Ms.

Which ones are you looking for?

Badboy

[PJ_Godzilla]

Which ones are you looking for?

Badboy

I really want one for the 109s G-14/K4 and for the Ki-84 and N1K2. Ideally, I'd get one for the 38, Spit 16, P-51B/D and La as well... I n tha torder of priority.

[Owlblink]

I really want one for the 109s G-14/K4 and for the Ki-84 and N1K2. Ideally, I'd get one for the 38, Spit 16, P-51B/D and La as well... I n tha torder of priority.

I would really love to see one for the 109G-14, 109K-14 and Spit 16 as well, if possible.

I've been flying the k-4 for a while in the DA and most people seem to love the spit16 in there, which I have a hard time flighting against. Maybe I have to learn to extend more for reversal room or something but I'd like to see what the numbers say for what would give me the best edge.

Thanks Badboy!

[PJ_Godzilla]

I would really love to see one for the 109G-14, 109K-14 and Spit 16 as well, if possible.

I've been flying the k-4 for a while in the DA and most people seem to love the spit16 in there, which I have a hard time flighting against. Maybe I have to learn to extend more for reversal room or something but I'd like to see what the numbers say for what would give me the best edge.

Thanks Badboy!

Funny, but I noticed, the other night, that it was fairly easy to extend away from a Spit-14 and some Hawgs in the K-4. The real problem I have with that machine is dealing with turners. I've been practicing lag rolling but all this eems to do for me is maintain some position above and behind from where I'm too far out to take a shot. It seems like, no matter what, I'm either taking hopeless high-speed tater shots or saddling up and making myself extremely vulnerable. The whole right-side energy fight is thus baffling to me. I mean, what the hell good is a D-9 at 400kts if you can never land a shot? All you get is a snap at that speed, typically.

[moot]

The Dora's guns and airframe combination never made sense to me.  Put an MK108 or MK103 in the nose instead and..

[Urchin]

Badboy, would it be possible to make diagrams for the ww1 planes? That would be much appreciated by me, and I am sure by everyone else that plays around in that arena.

[Badboy]

I really want one for the 109s G-14/K4

Ok, this will get you started.

The performance is very close. The analysis of their performance with flaps shows that these two aircraft are similarly closely matched as flaps are employed. 



The data for the G-14 is a bit dated, but should be ok. With performance this close I would expect an engagement to be decided by something other than turning ability. Of course, the G-14 might have the additional Gondolas, or one or other aircraft might have more fuel, and that could swing it. For example, if the G-14 had the Gondolas and 25% more fuel its sustained turn rate would drop by two degrees per second across the envelope and that could be decisive performance hit. Give the K4 25% more fuel and its sustained turn rate drops one degree per second below the G-14. Either way these aircraft are still closely matched and factors such as pilot ability, aircraft handling, fuel or configuration differences and possibly other performance factors are likely to have a more significant influence on the outcome.

Badboy

     

[boomerlu]

Badboy, I'm curious as to what type of software/data you use to generate these graphs?

[PJ_Godzilla]

Ok, this will get you started.

The performance is very close. The analysis of their performance with flaps shows that these two aircraft are similarly closely matched as flaps are employed. 
     

Flaps? I reckon those would only impact the left-hand (low-speed) extent of the envelope, right? I mean, corner speed is corner speed and lies above the speed at which you can extend flaps anyway...

Otherwise, thanks. Increasing alt tends to shift this all to the right, yes?

[Drano]

Flaps? I reckon those would only impact the left-hand (low-speed) extent of the envelope, right? I mean, corner speed is corner speed and lies above the speed at which you can extend flaps anyway...

Otherwise, thanks. Increasing alt tends to shift this all to the right, yes?

Many things are a factor in affecting turn rates. Altitude wouldn't be one of those as the speed is measured in indicated mph and that won't change with alt. The relative speed of the wind across your wings is what it is. But with thinner air up high you have to be moving faster through it to produce that. Alt will affect your engine's ability to produce a certain speed or not, however. Other factors include things like notches of flap if any, WEP on or off, and weight of fuel/guns/ords The corner speed in Badboy's diagrams are for one particular configuration, in the above case that would be 25% fuel, clean (no flaps or gondies etc) and at sea level. Change that configuration and the corner speed will move correspondingly.

Most people think that corner speed is etched in stone. That there's a set best turn speed and that's just not the case.

Drano

[PJ_Godzilla]

Many things are a factor in affecting turn rates. Altitude wouldn't be one of those as the speed is measured in indicated mph and that won't change with alt. The relative speed of the wind across your wings is what it is. But with thinner air up high you have to be moving faster through it to produce that. Alt will affect your engine's ability to produce a certain speed or not, however. Other factors include things like notches of flap if any, WEP on or off, and weight of fuel/guns/ords The corner speed in Badboy's diagrams are for one particular configuration, in the above case that would be 25% fuel, clean (no flaps or gondies etc) and at sea level. Change that configuration and the corner speed will move correspondingly.

Most people think that corner speed is etched in stone. That there's a set best turn speed and that's just not the case.

Drano

I disagree. My understanding is that the E-M is alt-specific. You cite the reasons why above but let's reiterate:

1. rho changes - therefore, anything rho-dependent changes - this includes lift and drag.
2. power output, and with it, powerloading changes.
3. max speed changes (true) - note that this alone would increase the size of the envelope, not to mention any other effects. Thus contradicting any assertion that the E-M won't change with alt.

As for your assertion that "altitude wouldn't affect turn rate" because speed is in indicated mph and since this won't change with alt, neither will the e-m  I found it baffling, perhaps just because of how it was written. Indeed, see Shaw, page 300. He states that corner WILL change with alt but that shoudl be relatively insignificant if we express indicated instead of true. He says no such thing about the e-m diagram of which corner velocity is but a part (if a critical one).

However, your intuitive statement about the speed/alt dependency of lift is correct.

Then, your last statement appears to contradict your earlier assertion - so you leave me a bit baffled.

Finally, yes, I'm aware that Badboy has outlined one config - it is on the plot. However, I wold also point out that he's clearly indicated that this is at SSL alt and state.

[PJ_Godzilla]

And,  I almost forgot to add, thanks and praise be unto Badboy. I figured that corner speed was a nose-low 225-250 in the beloved G-14 because I remember a magic moment at that speed and attitude in which I was outturning a lala. Clearly, under the right conditions and loadout, he should be able to outturn me - but it's close and, at the margin, little things like a slight weight edge - or perhaps alt, make a diff.

Badboy, can you say a few words on the trend impact of alt? - outside of the obvious and aforementioned top speed line increase.

[Badboy]

and for the Ki-84 and N1K2.

I just found an analysis I did of the Ki-84 v Spit16 a while back and I don't think I ever posted it.

Firstly I looked at the Sea Level performance with 25% fuel for both aircraft and it came out like this:



Which shows a clear advantage to the Spitfire at lower speeds where it has a slightly tighter sustained turn and a sustained turn rate advantage of about two degrees per second which would be decisive. The problem is that if you meet a good Ki84 pilot on line in a Spit16 the outcome will be anything but decisive. So, what happens when the Ki84 and Spit employ flaps?



Now the Ki84 can match the Spitfire's instantaneous turn performance very closely. Now let's see what happens when the Ki84 employs two notches of flaps:



Here the instantaneous performance of the Ki84 exceeds that of the Spitfire by around five degrees per second, speed for speed, in terms of air combat that is a very big advantage. But then of course the Spitfire pilot will employ his flaps also, and when both aircraft have their flaps extended their performance looks like this:



This shows that the Ki84 retains a sustained turn advantage of around two degrees per second while their turn radii are similar.

You can see from this that an engagement between these two aircraft will depend a lot on each pilot's ability to use flaps correctly, and the Ki84 has the ability to gain speed rapidly when nose low, which gives it the ability to hold energy better than the Spitfire, particularly in vertical fights or fights where the Ki84 makes good use of the vertical plane, combined with good use of flaps. This can all result in a fight that can go either way, the Ki84 with good use of the vertical and flap employment that tends towards lead pursuit at the top in the vertical, and lag pursuit at the bottom, and similar flap usage in Hi Yo-Yos. For the Spitfire pilot this will always be a difficult fight, unless the Ki84 fails to fly to its strengths.

As a disclaimer, I would add that those diagrams date back to version 2.12 patch 4 and while they may or may not match the current version my recent experience indicates that the conclusions are still valid.

Badboy